Hello, I just bought one of these cheap carburetors and I'm quite confused on where the Air/Fuel screw is, all i can find was the Idle screw. I did notice this one screw at the bottom but wasn't sure what it was, so I didn't want to start messing with it.

 

Number 13 in the picture. The fuel mixture above idle is controlled by the slide and main jet which is inside the bowl of the carb.

What kind of problems are you having? Every time I have worked on a chinese carb the main jet and air jet if equipped are too small and you need to take them out of the old carb, or buy new, or drill them out to the proper size.

If i understand correctly the main jet is for wide open throttle and the slide needle adjustments are more for mid range stuff.

 

The quad is running very rich, which is why I was looking for the air/fuel screw, before i start messing with the internals of the carb. I do know I could lower the needle a tad to make it help run a bit leaner.
So what is number 26? what does it do?

 

26 is the idle mixture screw that you have circled in your first picture.

Any idea where your float level is?
Or if you have a vacuum leak?

If you adjust the idle mixture all the way closed does it kill the motor? It should, is not you have a vac leak.

 

I'll have to get back to you on that, it's pretty cold this time of year where I'm located. I don't think i have a vacuum leak, but i will have to check then.